The divisions of the priests and Levites are ready for all the service of the house of God, and every willing man of every skill will be at your disposal for the work. The officials and all the people are fully at your command.”
As for the general charge that David gave his son to seek God and serve him, the book of the law was, in that, his only rule, and there needed no other; but, in building the temple, David was now to give him three things: - 1. A model of the building, because it was to be such a building as neither he nor his architects ever saw.
Commenting on 1 Chronicles 28:11-21
behold, the courses of the priests and Levites--They were, most probably, represented in this assembly though they are not named. also the princes and all the people--that is, as well the skilful, expert, and zealous artisan, as the workman who needs to be directed in all his labors. Next: 1 Chronicles Chapter 29
And, behold, the courses of the priests and the Levites, [even they shall be with thee] for all the service of the house of God: and [there shall be] with thee for all manner of workmanship every willing skilful man, for any manner of service: also the princes and all the people [will be] wholly at thy commandment.